1. Field of the Invention
The present invention relates to rotary machine monitors, and more particularly pertains to a monitor for providing a remote indication of the rotational speed of a silo unloader rotary collector ring. A conventional type of silo unloader for unloading grain through a top opening in a vertical side wall has a discharge chute and a stationarY collector ring suspended within the top portion of a silo by a cable harness. A rotary collector ring is rotationally mounted to the stationary collector ring and is attached to a frame member. A screw auger is mounted on the frame and a rotary drive causes rotation of the screw auger and rotation of the frame and rotary collector ring with respect to the stationary collector ring. The screw auger collects grain from the top of the silo and transmits the grain through the discharge chute exteriorly of the silo. The rotary collector ring is rotated by an electric motor drive through a belt system. Slipping of the drive belt can result in a substantial difference in the rotational speed of the rotary collector ring and the drive motor. Conventionally, an amp meter is utilized to provide a remote indication of the load on the drive motor to a ground level operation. The ground level operator controls a winch connected to the suspension harness for lowering the unloading apparatus within the silo, as the grain level therein decreases. During cold weather and wet conditions, the belt drive of the unloader slips with increasing regularity. Thus, the operator monitoring the amp meter observes a load reduction on the motor when the drive belt begins to slip. The operator then further lowers the apparatus within the silo, in the belief that the grain level has been reduced, thus reducing the load on the motor. In actuality, the unloader may already be submerged within the grain, thus preventing proper rotation of the device, due to the increased rotational resistance. In order to overcome this problem, the present invention provides a device which indicates the actual rotational speed of the rotary collector ring and provides a remote indication thereof to a ground level operator.
2. Description of the Prior Art
Various types of silo monitors are known in the prior art. A typical example of such a silo monitor is to be found in U.S. Pat. No. 4,047,434, which issued to N. Marsh et al on Sept. 13, 1977. This patent discloses a device for monitoring the depth of silage in a silo which includes a plurality of vertically spaced sensors. An electrical circuit includes a visual display for indicating the amount of material within the silo. U.S. Pat. No. 4,161,120, which issued to J. Cloarec on Jul. 17, 1979, discloses a wheel velocity sensor for indicating the rotational speed of a rotary element. A tooth rotor and a stator with a detecting head are mounted proximate the rotor teeth. The detecting head of the stator contacts the face of a resilient seal which is coated with a low friction material. U.S. Pat. No. 4,506,339, which issued to K. Kuhnlein on Mar. 19, 1985, discloses a device for measuring and monitoring the angular velocity of the shaft of a rotating machine. A pluralitY of sensors are positioned adjacent the shaft of the rotating machine for generating sequential pulses with periods proportional to the angular velocity of the shaft. U.S. Pat. No. 4,667,156, which issued to T. Machino et al on May 19, 1987, discloses a tooth sensing wheel of the type utilized in anti-lock breaking systems. U.S. Pat. No. 4,811,603, which issued to R. Bitetti on Mar. 14, 1989, discloses a tachometric generator including an input shaft connected to a drive take-off frame a vehicle, a main shaft connected to the input shaft by a resilient coupling to an output shaft to an external mechanical transmission. The speed of rotation of these shafts is detected by a magneto-electric sensor.
While the above mentioned devices are directed to rotary machine monitors, none of these devices discloses a monitor for providing a remote indication of the actual rotational speed of the rotary collector ring of a friction driven rotary silo unloader. Inasmuch as the art is relatively crowded with respect to these various types of rotary machine monitors, it can be appreciated that there is a continuing need for and interest in improvements to such rotary machine monitors, and in this respect, the present invention addresses this need and interest.